- bookworm 6.1.123-1
- bookworm-backports 6.12.9-1~bpo12+1
- testing 6.12.12-1
- unstable 6.12.12-1
- experimental 6.13.2-1~exp1
PERF-SCHED(1) | perf Manual | PERF-SCHED(1) |
NAME¶
perf-sched - Tool to trace/measure scheduler properties (latencies)
SYNOPSIS¶
perf sched {record|latency|map|replay|script|timehist}
DESCRIPTION¶
There are several variants of perf sched:
'perf sched record <command>' to record the scheduling events of an arbitrary workload.
'perf sched latency' to report the per task scheduling latencies and other scheduling properties of the workload.
Example usage:
perf sched record -- sleep 1
perf sched latency
------------------------------------------------------------------------------------------------------------------------------------------- Task | Runtime ms | Count | Avg delay ms | Max delay ms | Max delay start | Max delay end | ------------------------------------------------------------------------------------------------------------------------------------------- perf:(2) | 2.804 ms | 66 | avg: 0.524 ms | max: 1.069 ms | max start: 254752.314960 s | max end: 254752.316029 s NetworkManager:1343 | 0.372 ms | 13 | avg: 0.008 ms | max: 0.013 ms | max start: 254751.551153 s | max end: 254751.551166 s kworker/1:2-xfs:4649 | 0.012 ms | 1 | avg: 0.008 ms | max: 0.008 ms | max start: 254751.519807 s | max end: 254751.519815 s kworker/3:1-xfs:388 | 0.011 ms | 1 | avg: 0.006 ms | max: 0.006 ms | max start: 254751.519809 s | max end: 254751.519815 s sleep:147736 | 0.938 ms | 3 | avg: 0.006 ms | max: 0.007 ms | max start: 254751.313817 s | max end: 254751.313824 s
It shows Runtime(time that a task spent actually running on the CPU), Count(number of times a delay was calculated) and delay(time that a task was ready to run but was kept waiting).
Tasks with the same command name are merged and the merge count is given within (), However if -p option is used, pid is mentioned.
'perf sched script' to see a detailed trace of the workload that
was recorded (aliased to 'perf script' for now).
'perf sched replay' to simulate the workload that was recorded via perf sched record. (this is done by starting up mockup threads that mimic the workload based on the events in the trace. These threads can then replay the timings (CPU runtime and sleep patterns) of the workload as it occurred when it was recorded - and can repeat it a number of times, measuring its performance.)
'perf sched map' to print a textual context-switching outline of workload captured via perf sched record. Columns stand for individual CPUs, and the two-letter shortcuts stand for tasks that are running on a CPU. A '*' denotes the CPU that had the event, and a dot signals an idle CPU.
'perf sched timehist' provides an analysis of scheduling events.
Example usage:
perf sched record -- sleep 1
perf sched timehist
By default it shows the individual schedule events, including the wait time (time between sched-out and next sched-in events for the task), the task scheduling delay (time between runnable and actually running) and run time for the task:
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
-------------- ------ -------------------- --------- --------- ---------
79371.874569 [0011] gcc[31949] 0.014 0.000 1.148
79371.874591 [0010] gcc[31951] 0.000 0.000 0.024
79371.874603 [0010] migration/10[59] 3.350 0.004 0.011
79371.874604 [0011] <idle> 1.148 0.000 0.035
79371.874723 [0005] <idle> 0.016 0.000 1.383
79371.874746 [0005] gcc[31949] 0.153 0.078 0.022 ...
Times are in msec.usec.
OPTIONS¶
-i, --input=<file>
-v, --verbose
-D, --dump-raw-trace=
-f, --force
OPTIONS FOR PERF SCHED LATENCY¶
-C, --CPU <n>
-p, --pids
-s, --sort <key[,key2...]>
OPTIONS FOR PERF SCHED MAP¶
--compact
--cpus
--color-cpus
--color-pids
--task-name <task>
--fuzzy-name
OPTIONS FOR PERF SCHED TIMEHIST¶
-k, --vmlinux=<file>
--kallsyms=<file>
-g, --call-graph
--max-stack
-C=, --cpu=
-p=, --pid=
-t=, --tid=
-s, --summary
-S, --with-summary
--symfs=<directory>
-V, --cpu-visual
-w, --wakeups
-M, --migrations
-n, --next
-I, --idle-hist
--time
--state
--show-prio
--prio
-P, --pre-migrations
OPTIONS FOR PERF SCHED REPLAY¶
-r, --repeat <n>
SEE ALSO¶
2025-02-08 | perf |